Okay - I think i got it working now:-)
One thing that confused me was the fact, that i should use my polkadot extensions private key as a profile manager mnemonics on the play.grid.tf and not use a new created account as the profile manager.
Maybe it is the link from dashboard.grid.tf to play.grid.tf that made me think that i still was logged in with my polkadot account and therefore i should create a new account in the profile manager.
Maybe it could be a good idea to show the user some feedback about logged in or not. And use same feedback as the dashboard with a clear connect and disconnect button or in the future a list of profile managers accounts assigned to the polkadot account if possible.
Just to understand the bigger picture. Is it only a polkadot account / private key that can create a profile manager at the moment?
Now thanks for pointing me in the right direction - time to deploy and do some experiment